For white, you may want to consider Warhammer Lord Soth's magic wash.
It uses Vallejo Matte Medium (Transparent Raw Umber Hue), mixed with lots of water.
(It may take a few tries to get the mix right, but since you only have two ingredients, just add more water if it's too dark or more paint if it's too light).
Basecoat white and brush the mix on, and allow it to dry (it'll lighten as it dries). Then go back over the model with ivory on the high spots. This is how he gets the white on his troopers looking so good (like you, his guys go to battle in white pajamas too).
I've used this technique on my own troops, but the pix I have don't show it off very well. The sunlight tends to wash out the subtle shading of the raw umber hue. But if you check out WHL Soths army blog (probably on the second or 3rd page of the brush and pallet), you'll see it in full effect.